A man demonstrates an e-cigarette at a Chicago store. A new study has found marketing of e-cigarette brands climbing rapidly online. / Nam Y. Huhm AP

by Karen Weintraub, Special for USA TODAY

by Karen Weintraub, Special for USA TODAY

The market for e-cigarettes is exploding, with an average of 10 new brands entering the market every month for the last two years, and more than 7,700 total flavors, a new Internet survey found.

"The product has caught on fire," said Shu-Hong Zhu, a public health researcher at the University of California-San Diego who helped lead the research.

Rather than burning tobacco, e-cigarettes have a battery-powered heating cartridge that vaporizes liquid containing nicotine and/or flavorings. Most deliver a significantly lower level of nicotine than conventional cigarettes, and some data suggest they may help people quit smoking, Zhu said.

Products on the market when Zhu's team first did an Internet search in 2012 were more likely to resemble conventional cigarettes, according to the study, published Monday in the journal Tobacco Control. Products that have come on the market since are less cigarette-like, often dispensing the vapor from a device that looks like a fat fountain pen.

Zhu said he is doing additional research to see whether the newer brands are attracting new types of customers, such as children drawn in by candy flavors and marketing tactics reminiscent of big tobacco.

As long as e-cigarettes are primarily used to help quit smoking - and not to spur children to smoke - they will be a benefit to public health, said Michael Siegel, a tobacco control expert at the Boston University School of Public Health.

Siegel said he doesn't see flavored e-cigarettes as a "gateway" to smoking for children, even though there are many flavors that kids would find appealing. "It would be really hard to switch from a cherry e-cigarette to a Marlboro," he said. "In a way, the flavors are protective."

But Siegel said he's worried about proposed regulations from the Food and Drug Administration that would require companies to seek federal approval for each individual e-cigarette product. Such regulation would create an endless paperwork nightmare both for the companies and the federal government, he said, and would drive smaller companies out of business. The largest companies in the e-cigarette market are also the largest tobacco companies - and those with the least incentive to help people quit smoking, he said.

Instead, Siegel said the government should create minimum standards for e-cigarettes that protect users but don't stifle competition.

Maciej Goniewicz, a pharmacologist and toxicologist at the Roswell Park Cancer Institute in Buffalo, said there are some types of e-cigarettes that make him anxious. Brands with battery packs that offered a choice of output voltages, for instance, were quite safe at the lower levels, but released significant levels of toxins when heated to extremes, according to his research.

There should be a general standard for e-cigarettes, he said, setting maximum temperatures and levels of nicotine, along with consistent manufacturing practices and a list of approved flavorings.

Goniewicz said he's also very supportive of properly regulated e-cigarettes, used by people trying to quit. "Let's leave this product for the smokers, because it is very likely that this product is much safer [than cigarettes] and it might save their lives."